# This file is part of krakenex.
#
# krakenex is free software: you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the
# Free Software Foundation, either version 3 of the License, or (at your
# option) any later version.
#
# krakenex is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# General Public License for more details.
#
# You should have received a copy of the GNU General
# Public LICENSE along with krakenex. If not, see
# <http://www.gnu.org/licenses/gpl-3.0.txt>.


import json
import urllib

# private query nonce
import time

# private query signing
import hashlib
import hmac
import base64

from krakenex import connection


class API:
    """Kraken.com cryptocurrency Exchange API.
Public methods:
query_public
query_private
"""
    def __init__(self, key = '', secret = ''):
        """Create an object with authentication information.
Arguments:
key -- key required to make queries to the API (default: '')
secret -- private key used to sign API messages (default: '')
"""
        self.key = key
        self.secret = secret
        self.uri = 'https://api.kraken.com'
        self.apiversion = '0'


    def load_key(self, path):
        """Load key and secret from file.
Argument:
path -- path to file (string, no default)
"""
        f = open(path, "r")
        self.key = f.readline().strip()
        self.secret = f.readline().strip()


    def _query(self, urlpath, req = {}, conn = None, headers = {}):
        """Low-level query handling.
Arguments:
urlpath -- API URL path sans host (string, no default)
req -- additional API request parameters (default: {})
conn -- kraken.Connection object (default: None)
headers -- HTTPS headers (default: {})
"""
        url = self.uri + urlpath

        if conn is None:
            conn = connection.Connection()

        ret = conn._request(url, req, headers)
        return json.loads(ret)

    
    def query_public(self, method, req = {}, conn = None):
        """API queries that do not require a valid key/secret pair.
Arguments:
method -- API method name (string, no default)
req -- additional API request parameters (default: {})
conn -- connection object to reuse (default: None)
"""
        urlpath = '/' + self.apiversion + '/public/' + method

        return self._query(urlpath, req, conn)

    
    def query_private(self, method, req={}, conn = None):
        """API queries that require a valid key/secret pair.
Arguments:
method -- API method name (string, no default)
req -- additional API request parameters (default: {})
conn -- connection object to reuse (default: None)
"""
        urlpath = '/' + self.apiversion + '/private/' + method

        req['nonce'] = int(1000*time.time())
        postdata = urllib.urlencode(req)
        message = urlpath + hashlib.sha256(str(req['nonce']) +
                                           postdata).digest()
        signature = hmac.new(base64.b64decode(self.secret),
                             message, hashlib.sha512)
        headers = {
            'API-Key': self.key,
            'API-Sign': base64.b64encode(signature.digest())
        }

        return self._query(urlpath, req, conn, headers)